The present invention relates to a coated cutting insert with a wear-resistant coating scheme that exhibits wear indication and a method of making the same. More specifically, the invention pertains to a coated cutting insert with a wear-resistant coating scheme that exhibits wear indication via visually contrasting colors of an outer wear-indicating coating layer that operatively adheres to an alumina coating layer, as well as a method of making the coated cutting insert.
Milling cutters and other tools used for the removal of material from a workpiece (e.g., machining of a workpiece) sometimes present one or several cutting inserts. Each one of these cutting inserts exhibits a certain tool life so that from time-to-time the operator must replace the used cutting inserts with unused cutting inserts. The operator will make a complete replacement of the cutting insert when it has only one cutting edge. In reference to a cutting insert with multiple cutting edges, the operator will index the cutting insert to expose an unused cutting edge when the engaged cutting edge nears the end of its useful tool life.
It can be detrimental to the overall material removal operation for a used cutting edge to be placed back in service. Thus, it would be advantageous to identify easily a used cutting edge to avoid placing a used cutting edge back in service.
Heretofore, there have been coating schemes for cutting inserts useful to detect the use of a specific cutting edge. In this regard, U.S. Pat. No. 6,682,274 B2 to Vtsch et al. pertains to a coated cutting insert with wear indicating properties wherein the flank or flanks of the cutting insert according to the invention is (are) provided with a wearable indicating layer, having a color that differs from the color of the surface or layer underneath. The wear indicating coating layer does not extend to the cutting edge and is “sensitive enough, so that even a short-term use of the adjacent cutting edge leaves clear traces on the indicating layer.” See Abstract.
European Patent Application No. 1 757 389 A1, which was not published until Feb. 28, 2007 (the PCT equivalent (PCT WO 2006/067956) carries a publication date of Jun. 29, 2006), appears to disclose a coating arrangement on the surface of a cutting tool that comprises four basic layers. The layers are in the following order moving out from the substrate: third layer (next to substrate), first layer, second layer and fourth layer. The first layer is underneath the second layer and comprises titanium boronitride (TiBN) or titanium boron-oxynitride (TiBNO). The second layer is, “ . . . implemented as a single layer or a plurality of layers, by at least one selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide and a solid solution mainly including two or more of these components, and the second coating layer is located directly on the first coating layer.” The third layer is between the first layer and the substrate and includes TiC, TiN, TiCN, TiCNO, TiB2, TiBN, TiCBN, ZrC, ZrO2HfC, HfN, TiAIN, AlCrN, CrN, VN, TiSiN, TiSiCN, AlTiCrN, and TiAlCN. The fourth layer is the coating layer that functions as a wear indicating coating layer and can include TiCNO and is removed from the cutting area by blasting.
Kennametal Inc. of Latrobe, Penn. 15650 United States of America makes and sells a commercial prior art coated cutting insert. This prior art coated cutting insert presents a coating scheme as follows: a titanium nitride base coating layer on the substrate, a titanium carbonitride coating layer on the titanium nitride coating layer, a bonding layer that includes Ti, Al, O, C and N on the titanium carbonitride coating layer and an alpha-alumina coating layer on the bonding layer. During the manufacture of the prior art cutting insert, a titanium nitride/titanium carbonitride coating layer is applied to the alpha-alumina coating layer and then removed by blasting whereby the alpha-alumina coating layer experiences reduced tensile residual stress or compressive residual stress.
U.S. Pat. No. 7,153,562 to Rodmar et al. pertains to a coated cutting insert that includes a TiCON layer and wherein the titanium carbonitride is the outer coating layer.
U.S. Pat. No. 6,472,060 to Ruppi et al., as well as related issued U.S. Pat. No. 6,620,498 to Ruppi et al. and U.S. Pat. No. 6,652,913 to Ruppi et al., pertains to a coated cutting insert that includes in the coating scheme a nanocrystalline coating of Ti(C,N,O) applied via a MTCVD process at a temperature that ranges between 700-900° C. See Column 2, lines 36-45.
U.S. Pat. No. 6,015,614 to Ruppi pertains to a multi-layer coating scheme for a cutting insert wherein the process includes a post-coating blasting treatment. The '614 Patent appears to show an α-Al2O3 layer with a bonding layer ((Ti,Al)(C,O,N) thereon, as well as a single or multiple layer TiN scheme on the bonding layer. See Examples Nos. 9 and 10 in Table 3. The multiple layer TiN scheme comprises alternating layers of TiN and TiC. See Example No. 8 in Table 3. The '614 patent includes the step of blasting the surface of the coated insert using Al2O3 particles (320 mesh, medium grain size 30 μm). See Col. 3, line 66 through Col. 4, line 3.
U.S. Pat. No. 7,192,637 to Ruppi et al. pertains to disclose a multi-layer coating scheme for a cutting insert. The '637 Patent appears to show an α-Al2O3 layer with a bonding layer of Ti(C,O,N) (or Ti(C,N) [see Col. 2, lines 37-47]) thereon, as well as a TiN layer on the bonding layer. See Col. 4, lines 31-44. There is a TiCN/TiN coating scheme on the α-Al2O3 layer. See Col. 5, lines 1-3.
U.S. Pat. No. 6,379,798 to Yazaki appears to show an inner Al2O3 layer with a titanium carbonitroxide outermost layer. See Col. 3, lines 8-20. The outermost layer comes off when subjected to mechanical stress to provide wear-indicating properties via color differentiation. See Col. 2, lines 9-38. Along this line, U.S. Pat. No. 7,097,901 to Larsson et al. appears to disclose a layer of TiCxNyOz on an Al2O3 layer (see Col. 4, lines 55-59), and U.S. Pat. No. 7,132,153 to Zackrisson et al. appears to disclose a layer of TiCxNyOz on an Al2O3 layer (see Col. 4, lines 56-59).
U.S. Patent Application Publication No. US 2006/0177584 to Gates, Jr., et al. (assigned to the assignee of the present patent application) includes a disclosure of the coating combination of TiAlOCN/TiOCN. See Table 8 (Inventive Heat No. 9). However, this bonding arrangement is below the alumina layer so that the TiAlOCN/TiOCN coating scheme is a part of a modification scheme that is between the outer alumina coating and the inner TiCN coating layer.
U.S. Patent Application Publication No. US 2007/0128469 to Okada et al. presents a general description of the coating scheme that comprises a base coating, an intermediate coating and an outermost coating. In this regard, Paragraphs [0013]-[0021] read in part:                The surface-coated cutting insert of the present invention includes: an insert body having a substrate of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet or ceramics; and a base layer, an intermediate layer and an outermost layer which are provided on a surface of the insert body, in order from the insert body side; wherein a cutting edge is formed at an intersecting edge line region where a rake face and a flank face of the insert body intersect, the base layer and the outermost layer are made of a single layer or two or more layers formed of carbides, nitrides, oxides, or borides of one selected from the group consisting of periodic table Group IVa metals, Group Va metals, Group VIa metals, aluminum and silicon, or complex compounds thereof, and the intermediate layer is formed of primarily Al2O3, the outermost layer is removed so as to leave primarily the intermediate layer exposed on part of the insert body surface, including at least the flank face and a flank face-side cutting edge portion of the intersecting edge line region that is connected to the flank face, with the outermost layer being left on at least part of the rake face inside a boundary with the intersecting edge line region.        The outermost layer may be removed so as to leave primarily the intermediate layer exposed on the flank face and all of the intersecting edge line region.        The outermost layer may be removed so as to leave primarily the intermediate layer exposed from the flank face to a range inside the rake face from the boundary between the intersecting edge line region and the rake face.        The outermost layer may be removed so as to leave primarily the intermediate layer exposed within a range up to 2 mm inside the rake face from the boundary between the intersecting edge line region and the rake face.        The base layer or the outermost layer or both thereof may have a single layer or two or more layers formed of carbides, nitrides, oxides, or borides of one selected from the group consisting of Ti, Zr, Hf, and Cr, which are selected from periodic table Group IVa metals, Group Va metals, and Group VIa metals, and aluminum and silicon, or complex compounds thereof.        The intermediate layer may be a layer which includes Al2O3 at a content of 80 vol % or more.        At the flank face and at the flank face-side cutting edge portion, the intermediate layer may be exposed 70% or more of the surface area.        
The outermost layer may be removed by wet blasting.]
The '469 Okada et al. publication also appears to present variations of wet blasting to remove a portion of the coating from the as-coated cutting insert. See Paragraphs [0029]-[0033].
U.S. Pat. No. 5,372,873 to Yoshimura et al. discloses the benefits of shot peening a coated cutting insert. The shot peening can convert tensile stresses to compressive stresses. The shot peening can be localized so selected surfaces exhibit selected stress conditions. See Col. 6, lines 32-52. The relevant coating scheme comprises alumina that has a titanium carbonitride layer thereon, which in turn, has a titanium nitride layer thereon. See Col. 8, lines 4-10; Tests 5-8 and 13-16 in Table 2. The '873 Patent is technically along the lines of the following patents: U.S. Pat. No. 5,576,093 to Yoshimura et al., U.S. Pat. No. 5,374,471 to Yoshimura et al., and U.S. Pat. No. 5,681,651 to Yoshimura et al.
U.S. Pat. No. 6,884,496 to Westphal et al. discloses the basic benefits of dry blasting a coated cutting insert wherein there is an increase in the compressive stress. See Col. 2, lines 42-67. U.S. Pat. No. 4,674,365 to Reed discloses a mechanical treatment. U.S. Pat. No. 5,861,210 to Lenander et al., which discloses a TiCxNyOz layer on alumina (see Col. 2, lines 30-43), discloses that it is known to vary the blasting parameters (see Example 1, Col. 4, line 48 through Col. 5, line 11) to achieve different results.
United States Patent Application Publication No. US2006/0257690 to Bjormander (European Patent Application No. 1 717 348 A2 is the European counterpart) pertains to a coated cutting tool insert wherein the post-treatment (preferably blasting or brushing) removes the outermost coating layer on the edge-line and on the rake face.